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the skull would naturally be most effective in quite young persons when the skull was still pliable. The feeding on coarse food and the absence or imperfection of cooking the food would give more work for the jaws, and consequently the muscles would become more powerful. One effect of civilisation is to improve the commissariat and cuisine, and as a result the jaws become smaller, and project less and less beyond the level of the forehead, that is, they become "orthognathous." The teeth are reduced in size and number, and the masseter muscles having less work to do become smaller and less powerful, and consequently they exert less pressure on the side walls of the cranium, and so the skulls are not so narrow, especially in front.

That the jaw muscles do affect the skull has been shown. by Nehring,' who, from his studies on skulls of both sexes and of various ages of anthropoid apes and of dogs of different breeds, is of the opinion that the occurrence of a constriction between the orbital and cerebral portions of the skull has direct relation to the strength of the facial musculature, and more especially of the jaw muscles. If the skull of a muscular Eskimo dog be compared with that of a pug or a Bolognese lap-dog, it will be found that this constriction is very marked in the Eskimo dog, the zygomatic arches of which are widely outstanding, and all the muscular attachments strongly developed; but the constriction is scarcely noticeable in the pug, and is entirely wanting in the Bolognese lap-dog; the two latter exhibit feminine rounded forms of the corresponding parts of the skull, with a fullydeveloped musculature. In domesticated dogs, as in civilised man, the jaw is relatively fully developed, and there is a tendency to reduction of the last molar tooth.

1 A. Nehring, "Menschenreste aus einem Sambaqui von Santos in Brasilien unter Vergleichung der Fossilreste des Pithecanthropus erectus, Dubois," Verhandl. Berliner anth. Gesellsch., 1895-6.

It must not be overlooked that the decrease of the action of the jaw muscles is concomitant with rise in culture, that is, to increased mental activity, which is usually associated with increase in the volume of the brain. We have already seen that the statistics collected in the anthropometric laboratory in the University of Cambridge, as worked out by Venn and by Galton, show that the period of the growth of the brain is prolonged in students, as opposed to those of corresponding ages who cease to study.

It may be accepted as true in the main that the increase in the size of the brain, which is due to culture, is exhibited proportionately more in the breadth and height than in the length.

Thus culture may act in two ways on the skull; directly, by enlarging the volume of the brain, and therefore increasing the size of the skull; and indirectly, by causing a reduction of the jaw, which reacts again upon the skull. One is not surprised, then, to find that the higher races have, as a rule, a greater breadth in the anterior temporal region of the skull than the lower races.

The decrease in the size of the jaws and of the strength of their muscles induces a corresponding modification in the rest of the face. The action of the lower jaw upon the upper may be likened to the beating of a hammer on an anvil. When the jaw muscles are powerful the lower jaw is brought with a considerable force against the upper jaw, and consequently the arches which connect the upper jaw with the cranium must be proportionately well developed. Conversely the weakening of the jaw muscles permits, for example, the outer rim of the orbit and the zygomatic arch to be of a more delicate construction.

The increase of the brain causes the forehead to be at the same time broader and higher. This fact was noted by the sculptors of ancient Greece, and they increased the vertical

height of the forehead of some of their gods, so that, as in the case of Zeus, this human character was carried by them beyond human limits, when they wished to emphasise the benevolence and mental superiority of the Father of gods and men.

When at an indoor gathering we see a number of men with their hats off we notice that their heads vary in form. Some are small, others large; some have long heads, others have short ones; the head may be high or low, and the contours vary in diverse ways. These differences render the study of craniology peculiarly difficult, as it is almost impossible to describe most of them at the same time succinctly and intelligibly, and also because innumerable combinations of variable elements may occur in a collection of skulls from a single district.

Dr. D. G. Brinton, the well-known American anthropologist, has been so impressed with the latter fact, that he despairs of the study of craniology throwing any certain light on the racial problems of anthropology. Undoubtedly an immense amount of tedious labour has been expended by enthusiastic students on the study and description of skulls, but often, one must confess, with very meagre results. There certainly is a wonderful fascination in skulls; and craniology, which to the outside observer appears to be about as uninteresting a subject as could well be conceived, has lured its votaries to more and more persistent and painstaking effort. The present writer, who once sat in the seat of the scornful, has also yielded to the charming of craniology.

A very strong argument in favour of craniology is the assistance that it should render to prehistoric archæology and to the history of peoples. We have documentary and legendary records of the shifting of populations, and our archæological museums are full of interesting records of the

past.

It would be a matter of great importance if the skulls that are exhumed could also be brought in as evidence. We are again face to face with the question that confronted us when considering the colour of the eyes and hair.

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Upper and Side Views of a Kalmuk's and of a Negro's Skull;
after Ranke.

Can one particular head-form, or a restricted number of head-forms, be regarded as characteristic of a race or consanguineous group? And are these characters sufficiently constant to be of scientific value?

Before we can attempt to answer these two questions, it will be necessary to give a brief account of the methods and nomenclature of craniometry: Fortunately, a very short description will serve the present purpose, as we are concerned with only one or two aspects of the subject, and not with craniology as a whole.

On looking at a number of skulls from above, it is seen that they are all longer than broad, though some are less so than others, and that the contour is very varied. Some may have somewhat flat sides, others have gently rounded sides, or the skull may appear narrow in front and swollen behind; indeed, there may be great variation in this respect even in skulls which have the same relation of breadth to length. Skulls must also be looked at from the front, side, back, and underneath, and their peculiarities noted.

The character which is most frequently recorded is the ratio of the breadth of the skull to its length. One speaks loosely of a long or a narrow, or of a short or round skull, but such vague descriptions are of no scientific value. Anthropologists now adopt the plan of calculating indices which accurately express this numerical relation. The extreme length and breadth of a skull are measured, the breadth is multiplied by one hundred, and the total is divided by the length; the result is the cranial index.

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In other words the length is reduced to one hundred, and the ratio of the breadth to that is the index.

The altitudinal index is the ratio of the height either to the length or to the breadth.

Height x 100
Length.

= Index.

Height x 100
Breadth.

= Index.

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